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samples/gallery/windows/win32_window.cc

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// Copyright 2019 The Flutter team. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "win32_window.h"
#include "resource.h"
#include "shellscalingapi.h"
namespace {
// the Windows DPI system is based on this
// constant for machines running at 100% scaling.
constexpr int kBaseDpi = 96;
constexpr LPCWSTR kClassName = L"CLASSNAME";
// Scale helper to convert logical scaler values to physical using passed in
// scale factor
int Scale(int source, double scale_factor) {
return static_cast<int>(source * scale_factor);
}
} // namespace
Win32Window::Win32Window() {}
Win32Window::~Win32Window() { Destroy(); }
bool Win32Window::CreateAndShow(const std::wstring &title, const Point &origin,
const Size &size) {
Destroy();
WNDCLASS window_class = RegisterWindowClass();
HMONITOR defaut_monitor =
MonitorFromWindow(nullptr, MONITOR_DEFAULTTOPRIMARY);
UINT dpi_x = 0, dpi_y = 0;
GetDpiForMonitor(defaut_monitor, MDT_EFFECTIVE_DPI, &dpi_x, &dpi_y);
double scale_factor = static_cast<double>(dpi_x) / kBaseDpi;
HWND window = CreateWindow(
window_class.lpszClassName, title.c_str(),
WS_OVERLAPPEDWINDOW | WS_VISIBLE, Scale(origin.x, scale_factor),
Scale(origin.y, scale_factor), Scale(size.width, scale_factor),
Scale(size.height, scale_factor), nullptr, nullptr,
window_class.hInstance, this);
return window != nullptr;
}
WNDCLASS Win32Window::RegisterWindowClass() {
WNDCLASS window_class{};
window_class.hCursor = LoadCursor(nullptr, IDC_ARROW);
window_class.lpszClassName = kClassName;
window_class.style = CS_HREDRAW | CS_VREDRAW;
window_class.cbClsExtra = 0;
window_class.cbWndExtra = 0;
window_class.hInstance = GetModuleHandle(nullptr);
window_class.hIcon =
LoadIcon(window_class.hInstance, MAKEINTRESOURCE(IDI_APP_ICON));
window_class.hbrBackground = 0;
window_class.lpszMenuName = nullptr;
window_class.lpfnWndProc = WndProc;
RegisterClass(&window_class);
return window_class;
}
LRESULT CALLBACK Win32Window::WndProc(HWND const window, UINT const message,
WPARAM const wparam,
LPARAM const lparam) noexcept {
if (message == WM_NCCREATE) {
auto cs = reinterpret_cast<CREATESTRUCT *>(lparam);
SetWindowLongPtr(window, GWLP_USERDATA,
reinterpret_cast<LONG_PTR>(cs->lpCreateParams));
auto that = static_cast<Win32Window *>(cs->lpCreateParams);
that->window_handle_ = window;
} else if (Win32Window *that = GetThisFromHandle(window)) {
return that->MessageHandler(window, message, wparam, lparam);
}
return DefWindowProc(window, message, wparam, lparam);
}
LRESULT
Win32Window::MessageHandler(HWND hwnd, UINT const message, WPARAM const wparam,
LPARAM const lparam) noexcept {
auto window =
reinterpret_cast<Win32Window *>(GetWindowLongPtr(hwnd, GWLP_USERDATA));
if (window == nullptr) {
return 0;
}
switch (message) {
case WM_DESTROY:
window_handle_ = nullptr;
Destroy();
return 0;
case WM_SIZE:
RECT rect;
GetClientRect(hwnd, &rect);
if (child_content_ != nullptr) {
// Size and position the child window.
MoveWindow(child_content_, rect.left, rect.top, rect.right - rect.left,
rect.bottom - rect.top, TRUE);
}
return 0;
case WM_ACTIVATE:
if (child_content_ != nullptr) {
SetFocus(child_content_);
}
return 0;
// Messages that are directly forwarded to embedding.
case WM_FONTCHANGE:
SendMessage(child_content_, WM_FONTCHANGE, NULL, NULL);
return 0;
}
return DefWindowProc(window_handle_, message, wparam, lparam);
}
void Win32Window::Destroy() {
if (window_handle_) {
DestroyWindow(window_handle_);
window_handle_ = nullptr;
}
UnregisterClass(kClassName, nullptr);
}
Win32Window *Win32Window::GetThisFromHandle(HWND const window) noexcept {
return reinterpret_cast<Win32Window *>(
GetWindowLongPtr(window, GWLP_USERDATA));
}
void Win32Window::SetChildContent(HWND content) {
child_content_ = content;
auto res = SetParent(content, window_handle_);
RECT frame;
GetClientRect(window_handle_, &frame);
MoveWindow(content, frame.left, frame.top, frame.right - frame.left,
frame.bottom - frame.top, true);
SetFocus(child_content_);
}
HWND Win32Window::GetHandle() { return window_handle_; }